The present invention relates to polyamide-based compositions. It relates more particularly to polyamide-based compositions whose processability and especially mouldability is improved. It also relates to articles made from these compositions.
Polyamides are thermoplastic polymers which are known for their mechanical and dielectric properties, for their resistance to elevated temperatures and for their chemical inertness.
In addition, semiaromatic polyamides exhibit gas barrier properties which justify their use on a large scale in the manufacture of plastic packaging, chiefly in the packaging of beverages and foodstuffs.
Nevertheless, these polymers are tricky to process. In fact, during their melt processing as performed in extrusion or injection processes a gradual fouling of the equipment is found, owing to the accumulation and/or degradation of material at the screws, the barrels, the dies and/or the filters. When this fouling becomes too great, a disorderly detachment of the excess material can be observed, and this results in the appearance of faults in the manufactured articles. In the particular case of extrusion processing, the fouling is in most cases located at the filters and its main consequence is a gradual blocking of the latter. The pressure measured in front of these filters then increases uniformly and crosses a critical threshold; the processing of the resin must be stopped to undertake a complete cleaning of the equipment.
The present invention is aimed at remedying this disadvantage and consequently providing polyamide-based compositions whose processability and especially mouldability is improved. To this end, it relates to compositions comprising:
A) 100 parts by weight of polyamide
B) from 0.001 to 5 parts by weight of a processing agent chosen from fluoropolymers.